Another tranny Problem (what could it be?)

[homerbundy]

Hi, I have a 1991 4.0 OHV 4x4 Automatic and the following problem with the transmission:

Everything works perfect. When I shift into gear, the tranny reacts as it should. It shifts as usual from first into second gear, but won't shift up into the third...

There are no other signs or the usual suspects of a defect or dying transmission. Now I wonder what causes the problem, what is the problem and of course I wonder how much repair/work (cost ) this will cause.

Did anyone of you ever experience or hear about this or a similar problem and do you have any hints or suggestions for me. I'm really concerned...

Thanks for any help!

Bernd

 

[general x]

im currently out of commision because my tranny wont shift out of 1st unless i nail the gas til im at 4900 rpms, then play with the gas. If you get any info on this im hoping it will help me too

 

[homerbundy]

Oh that sounds bad! In fact it sounds a lot like the symptoms I found at a 74 Caprice Classic shortly before the tranny died completely. Hopefully it's not the same problem with yours...

 

[Mbrooks420]

Homer, whats the fluid look like? General X does it seem underpowered when it finally does shift? Sounds like you may have lost the second gear band, and the tranny might be overrevving, and shifting straight from 1st to 3rd. One time when my trans went out it did this.

 

[homerbundy]

Unfortunately I can't check the fluid by now because the car is still parked in Tyrol and I'm in Vienna thinking about the few oportunities to get it from there to my place (approx. 300 miles).
I don't think it can be the second gear band. It shifts as usual and stays in the second gear. The Explorer accelerates normal up to the max speed that's possible in second gear. Then it simply doesn't shift up...
(I'm really looking forward to drive it all the way from Tyrol to Vienna under such circumstances. It will take at least half a day and cost at least $75 on fuel...)

 

[MrShorty]

2-3 shift is controlled by the engine vacuum via the vacuum modulator. I'd check to see if there's any ATF in the vacuum line leading to the vacuum modulator and check the engine vacuum level in that hose.
Could a kickdown cable out of adjustment cause these symptoms? It's easy enough to reset, I might try that as well.

 

[Glacier991]

To that I'd also add for the benefit of GeneralX that the 1-2 shift uses the governor and you could have the imfamous sticky/stuck governor. An "trans in vehicle" repair btw.

 

[homerbundy]

Thanks MrShorty! I think and do hope you could be right. I once had a similar problem with a 74 Caprice. The transmission worked ok, but didn't shift into third gear. It was still possible to shift up manually by pulling into 2nd and then up into 3rd. I didn't have a chance to try this with my Explorer (since I don't have it here yet). Naturally I'd prefer a problem with the vacuum modulator over an expensive transmission repair or replacement (for which I wouldn't have the money anyway...)

I'd still be happy to get more opinions and suggestions! The mechanics here aren't experienced if it comes to automatic transmissions and so the more possible causes and cures I can give the on the way would be a big help!

 

[general x]

thank you guys!!!
Mbrooks420 i couldnt take a note on how much power i was getting from my tranny because when i hit the gas hard it would downshift and id be stuck in 1st again.
Glacier991 thanks for the info, you really seem to be a auto guru around here, i think ill take a look at the diary i heard about thanx

 

[Glacier991]

General... I think you will find the thread there helpful. On a side note, thanks for the kudos, but there are numerous folks here much smarter than me on the A4LD, and on auto transmissions in general. I'm just taking my time with it and doing a lot of research along the way sharing what I learn and learning from my mistakes. I offer my opinion when I have one, not to say it's right. The trannie I am rebuilding in the Diary thread is my 1st A4LD rebuild, but 2 more will follow in close succession. In reality what makes the thread most worthwhile, in my opinion, are the voluminous pictures illustrating things. I have tried to ask - what would *I* want to see if someone was explaining this to me? And then take THAT picture. Including the governor portion for those JUST doing the governor.

 

[general x]

Glacier- Thanks for the help, I am still pondering what i should do about my tranny (take it to a shop or tinker myself) i just dont want to fix the governer and find out somthing much bigger has broke inside, the tranny oil came out black and the filter had a whole in it...

Thread hyjacking finished

 

[homerbundy]

The Mistery Of The Self Healing Transmission

O.k., finally I've talked a buddy of mine into giving me a lift all the 300 miles up to Tyrol in order to get my very first Explorer. I expected to drive it all the way back at a max speed of 35 - 40 mph, but another story will have to be written:

After running out of gas 30 yards from a gas-station and out of electric power due to a weak battery :frustrate , I started the trip back home. If you can't go any faster than 40mph you simply don't wanna go on the Autobahn. So I chosed a different route of several byways and estimated about 10 hours for the trip.

As expected, the Explorer didn't shift at all and so I had to go at only some 30mph at 4500rpm. I tried several things, like using the kickdown, accelarating, slowing down, shifting into gear manually, etc. Nothing worked out.

All of a sudden and without any obvious reason, the transmission shifted into second gear and allowed a max speed of almost 50mph which I already appreciated a lot. I was tuly happy and continued my nightly journey through the Alps.

I took the route over "Steinpass", a long and winding road with several sharp turns. It's not the most popular route of course, but it's the shortest and if you have a slow car, it's not a bad choice.

On the way down from the pass, the car suddenly did a little "jump" and guess what: from that moent on the transmission worked absolutely perfect! It shifted through all gears including overdrive and I was totally happy.

After about 45 minutes (meanwhile I was driving on the Autobahn since everything worked perfectly), tha transmission suddenly shifted back into second gear (at a speed of some 80 mph). I had the cruise control set to that speed and the engine went up to almost 5500 rpm until I switched the criuse control off.

Now the max speed was 50mph again, which is a little uncomfortable on the Autobahn . But I decided to stay on it unless the conditions would become worse. Not much changed for about two hours: I was going at a speed of 50 with some 4500 rpm. I hated to see (and mostly hear) my poor Ex suffer, but I didn't see any alternative since I started to become really tired.

Some 60 miles before Vienna I stopped at rest area to take a short break. I left the engine running since I feared it might not start again due to the bad battery. After some 20 minutes I continued my ride.

When I entered the on-ramp, it felt like the tranny would work alright again and My feeling was right - it did . The last stretch of the way was nice and smooth and it was possible to go at 85 mph and 3000 - 3500 rpm and in overdrive.

But when I reached my drive here and drove around the corner, the tranny started to fool around again...

Now my beautiful Explorer is waiting outside and I'm sitting here trying to get some answers that might help to make us both feeling better. The tranny-problem is a little different to what I was told by the former owner when I bought it last week. So my description in earlier posts is apparently not 100% correct.

I don't believe the tranny could have a serious defect since it works absolutely perfect time after time and even for 45 minutes to over an hour. I didnÄt find out what makes it work fine and what turns it into an annoying problem again. First it started to work good after I used the kickdown and accelerated up to 5000 rpm. The second time I accelerated very moderately and it worked fine. Therefore there are also no obvious reasons for it to change back into a state where it won't shift up from the second.

I also noticed, that (while in the "weird mode") the tranny only delivers torque to the drivetrain when the engine's rpm get close to the currently driven speed. For example, if the car's rolling downhill at a speed of let's say 48 mph and the max speed you can reach in that gear is 50, it takes a high rpm rate to accelerate to this 50. Nothing would happen before and it seems like the transmission is switched to neutral´.

Again: after doing so for a while, the tranny starts to work completely fine. Then it won't again. I can't tell why, I can't tell what to do and what the problem might be and of course I don't know how to fix it.

Could anybody please tell me what's the problem and maybe how to solve it. I hope someone can help...

Kindest regards!
Bernd

 

[Mbrooks420]

I believe there is a plunger in these transmisions that is prone to sticking. I think this may be you problem, tho I am not sure. I can't remember the name. If it stuck once, it will likely stick again, so I'd keep it close to the house.

 

[Glacier991]

The symptoms you have are an odd assortment. The fact that it will operate "normally" is a good indication to my mind that there is nothing "mechanically" wrong with your transmission. The entire operation of the mechanical parts that actually shift and transmit power is controlled by the valve body and its components, aided by the vacuum modulator (including the throttle valve it operates) and the speed governor in the A4LD. I am suspecting the problem lies somewhere in this mix. ALL of these things can be accessed without removing the trqansmission from the car, though the vacuumm modulator is a ***** to get to with the exhaust in place.

In the "off the top of my head" category... let's think a little about each. If the valve body were pretty gunked up, and valve spools were sticking, it could produce symptoms as varied as imagination might allow - like yours. Same may also be true for a leaky separator plate in the valve body, but doubt your symptoms would be as variable. If the vacuum modulator throttle valve was sticking, it could do similar things. If the governor was sticking, it might account for some, but I do not think ALL of your symptoms.

In order I am going to guess your vacuum modulator throttle valve is sticking. If you can get to it, I'd suggest first that you remove the modulator and the throttle valve and pin and replace it with the steel one shown in the "MyA4LD Diary" Thread. That will not be an expensive thing to try and may solve your problem. Next I'd drop the valve body, and clean it good, removing each of the spools and reassembling it making sure nothing sticks. I'd reattach it using the thicker gaskets on both sides of the separator plate. While I had it out I'd add a new booster valve using O rings, and the MOD that prevents the shiift lever from comong too far forward (both discussed in that previous thread).

I'd wager that either of those things has a high probability of solving your problem. Very possibly the first.

Good luck. Keep us posted.

 

[general x]

Grrr, I actually knew what the plunger was called. LOL
Glacier, do you know if a C4??? will bolt up in my truck by chance? im not to worryed about overdrive but i want a reliable tranny (I heard its reliable)

Edit-92 XLT with 4WD and im assuming the C4 is auto

 

[Glacier991]

No the C-4 will not bolt up and far as I know no one makes an adapter. Sorry.

 

[general x]

Shoot, i thought i heard a tranny that would bolt up other than the A4LD.

Thanx thou

 

[Glacier991]

Someone in another thread says a C-4 will bolt up therough a C-5 bellhousing. I cannot verify the accuracy of this but it they are right I was incorrect in my previous answer. Do you really want a 3 speed?

 

[swak6287]

since we are talking about tranny, anyone know if i need to rebuilt mine? 99 sohc 2wd. shift on 1 then 2... slips to 3... slips to 4... goto 5. the 2-3-4 is fast... the rpm dont even get a chance to go up 500. then, it overheats as i cruise at 5th gear. i tried manual shift on 1 and 2.. and then D but then it slips to 5 again. when i come to a stop in gear, the rpm stays at 1500... and if i put it in neutral.. it goes as high as 2000. i added the sealer additive to it and it had not worked.. also.. the fluid is still red.
i think i have about 100,000 miles on it (big tires.... lost track).
any help is appreciated.

 

[general x]

Someone in another thread says a C-4 will bolt up therough a C-5 bellhousing. I cannot verify the accuracy of this but it they are right I was incorrect in my previous answer. Do you really want a 3 speed?

Thats what i heard...I think you needed a C5 bellhousing, Flexplate and torque converter to put a C4 in and to put a C5 in you needed the C5's Bellhousing Torque converter and flexplate